"You will keep in perfect and constant peace the one whose mind is steadfast [that is, committed and focused on You—in both inclination and character], Because he trusts and takes refuge in You [with hope and confident expectation]." Isaiah 26:4
You are looking in the wrong place. You are under condemnation from the devil. You need to know that the blood of Christ has paid for your sins. Once you have confessed your sin, you are forgiven. God wipes the record of sin from your book of life. He forgets your sin, so why should you keep punishing yourself? Satan is the accuser of the brethren, God is merciful and gracious.